Abstract
BACKGROUND:
Several large, randomized trials established the benefits of adjuvant trastuzumab with chemotherapy. However, the benefit for women with small, node‐negative HER2‐positive (HER2+) disease is unknown, as these patients were largely excluded from these trials. Therefore, a retrospective, single‐institution, sequential cohort study of women with small, node‐negative, HER2+ breast cancer who did or did not receive adjuvant trastuzumab was conducted.
METHODS:
Women with ≤2 cm, node‐negative, HER2+ (immunohistochemistry 3+ or fluorescence in situ hybridization ≥2) breast cancer were identified through an institutional database. A “no‐trastuzumab” cohort of 106 trastuzumab‐untreated women diagnosed between January 1, 2002 and May 14, 2004 and a “trastuzumab” cohort of 155 trastuzumab‐treated women diagnosed between May 16, 2005 and December 31, 2008 were described. Survival and recurrence outcomes were estimated by Kaplan‐Meier methods.
RESULTS:
The cohorts were similar in age, median tumor size, histology, hormone receptor status, hormone therapy, and locoregional therapy. Chemotherapy was administered in 66% and 100% of the “no trastuzumab” and “trastuzumab” cohorts, respectively. The median recurrence‐free and survival follow‐up was: 6.5 years (0.7‐8.5) and 6.8 years (0.7‐8.5), respectively, for the “no trastuzumab” cohort and 3.0 years (0.5‐5.2) and 3.0 years (0.6‐5.2), respectively, for the “trastuzumab” cohort. The 3‐year locoregional invasive recurrence‐free, distant recurrence‐free, invasive disease‐free, and overall survival were 92% versus 98% (P = .0137), 95% versus 100% (P = .0072), 82% versus 97% (P < .0001), and 97% versus 99% (P = .18) for the “no trastuzumab” and “trastuzumab” cohorts, respectively.
CONCLUSIONS:
Women with small, node‐negative, HER2+ primary breast cancers likely derive significant benefit from adjuvant trastuzumab with chemotherapy. Cancer 2011;. © 2011 American Cancer Society.